Researchers Examine Overdiagnosis of Breast Cancer

Study argues for more balanced information for patients before making a treatment decision.

Breast cancer patients need to be provided with objective, balanced, and uncontested information regarding the treatment of their disease, according to a recent analysis.

A study published recently in The BMJ examined the growing debate surrounding overdiagnosis of breast cancer. A panel in the United Kingdom in 2012 estimated approximately 19% of breast cancers diagnosed in women who underwent mammogram screening were overdiagnosed, while other estimates have found overdiagnosis above 50% or less than 5%.

Study author Alexandra Barratt, a professor of Public Health at the University of Sydney, noted the importance of achieving a consensus on these rates.

Early estimates of screening have been found to reduce the risk of breast cancer death by approximately 30% in women over 50 years, which prompted publicly funded mammography screening programs in numerous countries during the 1980s and 90s.

While there have been significant gains in the detection of early breast cancer, the rates of advanced cancer have dropped slightly or remained relatively stable, the study noted. This indicates mammography screening is finding low risk or non-progressing breast cancer that is not life threatening, according to the study.

This factor is concerning to researchers, as 99% of women with breast cancer detected during screening undergo surgery, while approximately 70% receive radiotherapy and hormone therapy.

“If around 20% of these breast cancers are overdiagnosed, then about 20% of these women are undergoing treatments to ‘cure’ a disease which they would never had had without screening,” Barratt wrote.

Providers are also urged to use caution before utilizing new breast imaging technologies or extended screening to wider age groups, until the net benefit for patients has been demonstrated in high quality clinical studies “based on demonstrated ability to achieve equivalent benefit to harm ratios and not on the assumption that increased detection will achieve a net benefit."

She also wrote that more balanced information and participation targets should not be considered a marker of health service quality.

"Breast cancer research has led the way in developing awareness of the potential harms of overdiagnosis and overtreatment among asymptomatic people who participate in cancer screening programs," Barratt concluded. "Increasing awareness and understanding of overdiagnosis in relation to the early detection of lung and thyroid cancers, as well as breast and prostate cancers, is needed and should be prioritized in public communication initiatives."